Facebook Privacy Settings?

[AIM]

Two ways of doing it
1) edit each post individually.
2) if you want to blanket allow these people to see everything that they were previously blocked from but still retain the ability to block them again in future. Transfer them to a new group under a different name and empty the old group. Since the filters are based on the groups, the filter will remain but they will no longer be in the filtered group and hence be able to see the posts.